The present invention relates to a process for manufacturing a product of glassy carbon, and more specifically to a method of manufacturing a structural member of glassy carbon used in a semiconductor manufacturing apparatus under elevated temperature of 500.degree. C. or higher.
Structural members made of glassy carbon are excellent in chemical stability and mechanical strength, and therefore they are used in portions of, for example, a semiconductor manufacturing apparatus, which are exposed to high temperature and require high mechanical strength.
The conventional process for manufacturing a structural member of glassy carbon will now be briefly described. First, a raw material resin is polymerized in a mold, and cured, thus obtaining a semi-processed piece having a predetermined shape. Then, the piece is baked. The baked piece is subjected to machining and grinding, and thus a product of a final shape is obtained. The obtained product is subjected to ultrasonic cleaning in pure water, and lastly, it is inspected of dimensions, shape and surface defection.
In the conventional manufacturing process, as described above, after baking of the molded piece, machining process is carried out to obtain a product to have a final shape. However, during the machining process, fine cracks or scratches (to be called as micro-cracks hereinafter) may be created.
When cyclic stress is applied at elevated temperature onto to such a glassy carbon material, or when thermal stress by exposure to temperature changes is applied thereto, micro cracks grow to become fatigue cracks. As a result, the glassy carbon product is broken after relatively short time.